You can use some techniques to minimize the time it takes to transfer the image files you have in your web:
- Reduce the amount of graphics on your web pages to
the minimum necessary to support your goals. Then
maybe shave off some more graphics beyond that.
Every image on your site should either:
- carry important information content (for example, historical photos at www.whitehouse.gov); or
- provide navigation cues (for example, icons or navigation bars, such as on Yahoo!); or
- provide aesthetic enhancements that add to the value of the information for the target audience. The people interested in the latest movie release from Paramount definitely expect more sizzle and graphics than the audience interested in Unix reference information.
- Reuse graphics that are at your site. When your users have their browser caching enabled, they can download an image once and their browser will display that image wherever it is referenced. If you have a logo or repeated graphic, reference the same graphics file on every web page where it occurs. You can therefore get more use out of the graphic with no additional cost in time to your user.
- Choose the best image format. If you are using a photograph, continous tone art or graphics with lighting, JPEG is the format to use. If you have a line drawing, flat art, or a cartoon, the GIF format is a good choice.
- Lower your standards for quality. For your JPEG images, using an image tool, you can choose the degree of "lossiness" when storing the JPEG image. There will be some degredation of image quality, but your payoff is in a faster image to the user.
- Give the browser some hints. Use the Height and Width attributes of the IMG element for every image in your web. This will help browsers lay out the page and put down some text for the user to read while the images download. This doesn't speed up the downloading of the images, but it reduces the time between the user requesting your web page and getting something useful to see.
- Get progressive or interlaced. You can use tools for making your JPEG or GIF image appear on the screen in stages--so that a user sees your image in stages while it comes into focus. Look for interlaced GIF tools or "progressive JPEG" tools to do this.
- Reduce, reduce, reduce. A good article setting out some ideas on reducing image size is at webreference.com